Add serving time metric for all files

4 files changed, 14 insertions, 4 deletions

diff --git a/app.go b/app.go
index 217f9db7..38744e93 100644
--- a/app.go
+++ b/app.go
@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"os"
 	"sync"
+	"time"
 
 	ghandlers "github.com/gorilla/handlers"
 	"github.com/rs/cors"
@@ -257,6 +258,9 @@ func (a *theApp) accessControlMiddleware(handler http.Handler) http.Handler {
 // return a 404 Not Found response
 func (a *theApp) serveFileOrNotFoundHandler() http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		start := time.Now()
+		defer metrics.ServingTime.Set(time.Since(start).Seconds())
+
 		domain := request.GetDomain(r)
 		fileServed := domain.ServeFileHTTP(w, r)
 
diff --git a/internal/serving/disk/reader.go b/internal/serving/disk/reader.go
index 38d055cf..949dd4e0 100644
--- a/internal/serving/disk/reader.go
+++ b/internal/serving/disk/reader.go
@@ -17,7 +17,7 @@ import (
 
 // Reader is a disk access driver
 type Reader struct {
-	fileSizeMetrics *prometheus.GaugeVec
+	fileSizeMetric *prometheus.GaugeVec
 }
 
 func (reader *Reader) tryFile(h serving.Handler) error {
@@ -144,7 +144,7 @@ func (reader *Reader) serveFile(w http.ResponseWriter, r *http.Request, origPath
 		return err
 	}
 
-	reader.fileSizeMetrics.With(prometheus.Labels{"serving_type": "disk", "content_type": contentType}).Set(float64(fi.Size()))
+	reader.fileSizeMetric.With(prometheus.Labels{"serving_type": "disk", "content_type": contentType}).Set(float64(fi.Size()))
 
 	w.Header().Set("Content-Type", contentType)
 	http.ServeContent(w, r, origPath, fi.ModTime(), file)
@@ -172,7 +172,7 @@ func (reader *Reader) serveCustomFile(w http.ResponseWriter, r *http.Request, co
 		return err
 	}
 
-	reader.fileSizeMetrics.With(prometheus.Labels{"serving_type": "disk", "content_type": contentType}).Set(float64(fi.Size()))
+	reader.fileSizeMetric.With(prometheus.Labels{"serving_type": "disk", "content_type": contentType}).Set(float64(fi.Size()))
 
 	w.Header().Set("Content-Type", contentType)
 	w.Header().Set("Content-Length", strconv.FormatInt(fi.Size(), 10))
diff --git a/internal/serving/disk/serving.go b/internal/serving/disk/serving.go
index 84945c8d..94a6d001 100644
--- a/internal/serving/disk/serving.go
+++ b/internal/serving/disk/serving.go
@@ -8,7 +8,7 @@ import (
 
 var disk = &Disk{
 	reader: Reader{
-		fileSizeMetrics: metrics.ServingFileSize,
+		fileSizeMetric: metrics.ServingFileSize,
 	},
 }
 
diff --git a/metrics/metrics.go b/metrics/metrics.go
index 1950eb77..949ffa1e 100644
--- a/metrics/metrics.go
+++ b/metrics/metrics.go
@@ -82,6 +82,12 @@ var (
 		Name: "gitlab_pages_serving_file_size",
 		Help: "The size in bytes for each file that has been served",
 	}, []string{"serving_type", "content_type"})
+
+	// ServingTime metric for time taken to find a file serving it or not found.
+	ServingTime = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "gitlab_pages_serving_time",
+		Help: "The time (in seconds) taken to serve a file",
+	})
 )
 
 // MustRegister collectors with the Prometheus client